Developments in electronics has led to the widespread use of mobile electronic devices such as mobile phones and notebook personal computers and vehicle-mounted electronic devices. Compact multi-functional electronic devices have been recently demanded.
In order to manufacture the compact multi-functional electronic devices, various semiconductor elements such as ICs and LSIs are used. This leads to a reduction in the noise resistance of electronic devices.
Bypass capacitors such as film capacitors, monolithic ceramic capacitors, and semiconductor ceramic capacitors are connected to power supply lines of ICs and LSIs such that the electronic devices have high noise resistance.
These capacitors absorb low-voltage or high-frequency noise and do not absorb high-voltage pulses or static electricity. Therefore, the application of the high-voltage pulses or static electricity to the electronic devices can cause the malfunction of the electronic devices or the breakage of semiconductor elements and can particularly cause the breakage of compact capacitors having low capacitance.
Boundary insulative layer-type monolithic semiconductor ceramic capacitors having a varistor function have been proposed. The boundary insulative layer-type monolithic semiconductor ceramic capacitors contain SrTiO3 and have high noise-absorbing properties, good temperature stability, good frequency stability, high pulse resistance and high pulse-absorbing properties.
For example, Patent Document 1 discloses a boundary insulative layer-type monolithic semiconductor ceramic capacitor containing Sr(1-x)BaxTiO3, MnO2, SiO2, and 0.05 to 5.0 mole percent of at least one member selected from the group consisting of Nb2O5, Ta2O5, V2O5, W2O5, Dy2O3, Nd2O3, Y2O3, La2O3 and CeO2, the total MnO2 and SiO2 content being 0.2 to 5.0 mole percent. In Sr(1-x)BaxTiO3, the content of Ti is excessive and the inequalities 0.95≦Sr(1-x)Bax/Ti≦1.00 and 0<x≦0.3 exist.
According to Patent Document 1, the boundary insulative layer-type monolithic semiconductor ceramic capacitor usually absorbs low-voltage noise and/or high-frequency noise and functions as a varistor when a high voltage such as a pulse or static electricity is applied to the boundary insulative layer-type semiconductor ceramic capacitor. A process for co-firing a ceramic material and a material for forming internal electrodes can be used to manufacture the boundary insulative layer-type monolithic semiconductor ceramic capacitor.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 2-240904